Method of making bifocal-lens blanks.



W. I. SEYMOUR.

METHOD OF MAKING BIFQOAL LENS BLANKS. APPLICATION FILED JUNE 7, 1909.

1,024,486. Patented A t. 23, 1912.1

* icy li g mm"? l UNITED STATES WALTER I. SEYMOUR, OF CHICAGO, ILLINOIS,:ASSIGNOR, BY MESNE ASSIGNMENTS,

PATENT OFFICE.

TO UNITED BIFOCAL COMPANY, OF NEW YORK, N Y. A CORPORATION OF'NEW YORK.

of'Chicago, in the county of Cook, in the ,State of Illinois, haveinvented new and useful Improvements in Methods of Making Bifocal-LensBlanks, of which the following, taken in connection with. theaccompanying drawings, is a full, clear, and exact description.

This invention relates to certain improvements in the method of makingbifocal lens blanksand refers more particularly to the art of uniting bywelding two or more layers or bodies of glass differing inkind or indexto form the blank from which the lens is to be ground and cut in theusual manner.

In my Patent No. 914,316 Lhave' disclosed- 'a method of forming bifocallenses in which the layers or bodies pf glass are united by fusion atthe same temperature on the blow pipe and then' partially formed in asuitable mold, while in my pending application No. 493,974, filed May 4,1909, I have also sliown and described a method of making bifocal lensesconsisting in uniting ithe glasses of-a; different kind or indextogetherv by allowing the plastic layers to rest one upon the. other andupon a suitable mold ,so as totake the form of such moldby their owngravity" 1 The subject matter of my present application is animprovement upon the methods "shown .in the patent and application abovereferred to in that itcontemplates the uniting of two or. more layers ofglass of-difien' 'ent' index such as lead glass and crown glass byfirstblowing .one' plastic' layer against thecurved dies of a 'moldand thenblowing the other plastic layer against the .first formed layer in suchmanner that only a comparatively 'small portion of the lead glassremains inse arably united to the crown glass, the 'rest being brokenaway, thereby econo'mi'zing materially'in time and labor necessary ingrinding or'finishing the blank This pressing one thin layer, aslead'glass, against the inner surface'of the mold andthe-n iminediatelyafterward, while the firstlayer is still softened by heat,then heating asecond layer of'crown' lass to softness under'a diflerent degree'otemperature from thatof the lead glass and blowing the softened crownglass against the inner surface of the first named layer, whereby the'two layers become welded at their points of contact,

Specification of Letters Patent.

METHOD or; MAKING BIrooA -LnNs BIZANKS Patented Apr. 23, 1912.

Application filed June 7, 1909. Serial No. 500,626.

suitable chambers being provided around the die or dies of-the mold intowhich portions of the outer layer, or lead glass, are

deflected to such an extent as to lie beyond the plane of contact of thelayer of crown able pontour and then similarly pressing or blowing theother layer against the high face or surfaces of one or more/dies ofsuit-' points of the first .named layer while the latter is still in theplastic state, thereby trapping the air in the space surrounding vthepoints of contact and separating the parts of thelayers adjacentsuchspace so that. when the united layers are removed from the mold andannealed, the portions of the lead glass layer inclosing the air spacesmay be readily broken away leaving a comparatively small but clean cut.disk of such:

lead glass inseparably united to the crown glass,thus removing aconsiderable surplus of'the'glass from the blank and materially reducingthe time and. labor required to grind such blank to the the'finishedlens;

Other objects and uses will be brought out in the following description:I

In the drawings-Figure l is a horizontal sectional view of amultisidedmold showing the two cylindrical layers-of glass as united at the'highpoints ofthe mold, ready to be desired contour for "removed for theannealing process. Fig. 2

.is a vertical sectional View of the samemold. Fig. 3 is a plan of oneof the lens blanks before'the surplus lead glass has been broken line H,Fig.3. 5 is a plan of one of the lens blanks after the surplus leadglass has been broken away. Fig. 6 is a sectional 1g. 5. v The moldshown in Figs. 1 and 2 comprises a series of sections -1. arranged edgeto edge about a common center'an'd hinged togetherv at their meetingedges by away. Fig. 4 is a sectional view taken on.

. view of the finished lens, the dotted lines indicating the sectiontaken on. line 6 -6,;

hinge pins 2-.which are removable to chamber -5- which is inclosed by asuit able housing or partition. -6- having a somewhat sharp or V-shapedinner edge lying in nearly the same plane as the curved surface -t-.Each die -4 is, therefore, surrounded by a housing or partition -6spaced apart therefrom to form the intervening chamber 5- and may beeither circular in form, as shown at the center or left hand, Fig. 2, ormay be rectangular as shown at the right of said figure, the size of thehousing determining the size of the lens blank.

The dies 3- may be located centrally of the res ective housings, shownat the left of Fig. 2, or may be located eccentrically, as

shown at the center and right of the same figure, the location of suchdie determining the point of union of the two layers which are to formthe lens blank.

The mold sections 1 may be made of cast iron or any other suitablematerial, but the dies 3 are usually made of separate pieces of metaland their inner faces smoothly polished or ground to the desired contourto give the sections of the blank the desired curvature in the finishedlens.

The base of each housing is provided with one or more air vents 7communicating with the chambers 3 to permit the es cape of air therefromduring the formation or blowing of the lead glass against the surfacesof the dies -3.

The process consists in first gathering upon the blow pipe a suitablequantity of previously melted lead glass, then inserting it into themold and quickly blowing or expanding it against the inner sides of themold with sutticient pressure to cause portions of the glass to pressagainst and assume the same contour as the faces 4 of the dies -3, andat the same time to cause otherportions to impinge against the knifeedges of the partitions 6,, the portions of the glass bet-ween the dieand surround-- ing housing being depressed into the chambers 5, suchdepression being readily ad mitted by the escape of air from saidchambers through the ports -7. This operation produces a comparativelythin glass cyl ma ines 8 having depressed marginal edges 9-, the disk 8consisting of that por tion of the glass which is coextensive with thearea of the die surface 4 while the marginal portion -9 comprises thatportion which lies between the partition 6- and periphery of the die. Assoon as this first layer of lead glass isproperly distributed over theinner surfaces of the dies and housingsof the mold, the portionattached'to the blow pipe is broken ed in a.

manner well known to those skilled in the art, leaving the upper end ofthe glass cylinder open.

Immediately upon the breaking away of the upper portion of the leadglass cylinder, and while the latter is still in a softened condition, asecond body of previously melted crown glass is gathered upon the end ofanother blow pipe and immediately inserted into the lead glass cylinderand expanded against the inner sides thereof in such manner as to pressevenly against the high points thereof, or rather against the disks 8-and portions immediately adjacent the knife edges of the partitions orhousings 6 During this last operation the crown glass cylinderwhichassumed a cylindrical form first contacts with the high points orsections of the disks 8- and gradually increases its area of contactfrom the center toward the periphery, thereby gradually expelling theair and forming a smooth and perfect welding between the two layers, andas this inner cylinder of crown glass con-- tinues to expand, itcontacts with the high points at the inner edges of the partition: 6-,thereby trapping the air and formingair chambers between portions of theadjacent layers in registration with the chamhers 5-. 4 After the innerlayer or cylinr der of crown glass has been pressed or BX- pended byblowing against the high points of the outer cylindrical layer of leadglass, these two layers become inseparably welded at such points, and byseparating the sections 1 of the mold in the manner previouslydescribed, the cylinders may be removed while the inner cylinder isstill attached to the blow pipe and subjected to the annealing process,which is well known in this art, and the unwelded portions of the leadglass which are separated from the crown glass by the spaces 9 arebroken away leaving only the disks 8inseparably welded to the crownglass.

The somewhat sharp inner bearing edges of the partition or housing 6form more or less V-shape channels which define the outline of the lensblank and enable said blanks to be easily broken out from the main bodyon these lines ready to be ground and finished into the form of lenses,as --A-,'

surrounding its junction with the crown glass has been previously brokenaway, thus removing a large part of the surplus lead glass, leaving justenoughto permit the desired finish of the lens to give the necessaryoptical effects in the finished lens. By this method the surfaces of thelens sections-are air finished in the simple operation of blowing, and Iam thereby enabled to obtain a perfect andflawless union of the twoparts without liability of excessive loss by breakage during the processof grinding, this breakage being reduced to a minimum by reason of thefact that the disks are united after being reduced to a plasticcondition under different temperatures, thereby avoiding the unequalexpansion and contraction incidental to the uniting of similarlens-sections by reducing them to a plastic condition under the-sametemperature. What I claim is 1. The herein described-method of makingbifocal lens blanks consisting in uniting two bodies of glass differingin kind or index in a suitable mold while such bodies are in a plasticcondition and changing the contour of a portion of the uniting surfacesof such bodies while in the mold.

2. The herein described method of making bifocal lens blanks consistingin uniting two bodies of glass differing in kind or in-- a portion ofthe contacting surfaces of said bodies the curvature desired in thefinished lenses while both bodies are still in" the mold. 4c. The hereindescribed method of making bifocal lens blanks consisting in uniting twobodies of :glass differing in kind or index while in a plastic conditionwithin a suitable mold, changing the contour of a portion of the unitingsurfaces'of said bodies while still in the mold and removing by breakingaway a portion of one of the layers around their uniting surfaces.

5. The herein described method of making bifocal lens blanks consistingin uniting two bodies of glass differing in kind or index within asuitable mold while said bodies are in a plastic condition, separatingportions of said bodies around their uniting surfaces while both bodiesare still in the mold and breaking away portions of one of said layersat its points of separation from the other layers.

6. The herein described method of making bifocal lens blanks consistingin uniting portions of two bodies of glass differing in kind or indexwithin a suitable mold while said bodies are in a plastic conditionfaiidsepa rating other portions of said bodies on definite lin'es surroundingtheother contacting portions, and removing by. breaking away theportionof one body whichis separated from the other body.

7. The herein described method-of making bifocal lens blanks consistingin impressing different portions of a body of plastic glass againstraised surfaces one within the other in such manner as to cause themtervemng portions of such glass to be depressed between such surfacesand afterward impressing another body of glass against the raisedsurface of the first named body while both bodies are softened by heatand subsequently removing by breaking away the depressed portion of thefirst named body. V

8. The herein described method of making bifocal lens blanks consistingin providing a mold with raised surfaces one surrounding the otherandvspaced apart therefrom to form an intervening depression, impressinga plastic body of glass against said surface and intotheinteryeningspace and afterward impressing another body of glass ofdifferent kind or index against the portions of the first body which areimpressed against said raised I surface.

9. The herein described method of making bifocal lens blanks consistingin providing a against'said surface and into the intervene ing' space,then blowing another plastic body of glass against the inner contactsurface for the two bodies while softened by heat.-

10. The herein described process of mak- 1n bifocallens blanksconsisting in providing a mold with a plurality of sets of contactingsurfaces and intervening depressions between those of each set, thenblowing a plastic body of glass against the contact surface of each setand into the intervening i space, afterward blowing another plastic bodyof glass against the portions of the first named body which are incontact with said surfaces, and finallybreaking away the portions of thefirst named body which are depressed into the recess.

In witness whereof I have hereunto set my hand this 3rd day of June,1909.

WVALTER I. SEYMOUR.

Witnesses:

SMITH AHHARRIMIAN, DAVID Moons.

Copies of this patent may be'obtained for nve'cents each} by'aidressiiigtho"0ommi:aioner ot' I'atents,

Washington, D. 0." p

